Cast iron tap – through and blind holes

Straight flute tap for cast irons and short-chipping materials, in through and blind holes. Broken chips, TiCN against abrasion.

ISO K

ISO N

Through and blind

TiCN

M2 – M36

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Geometry by material

Chamfer, helix and rake chosen for the material

DIN 371 / 376 sizes

Metric, fine, pipe and inch, also custom made

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Description

Technical drawing

At a glance

Hole type	Through holes and blind holes
Geometry	Straight flutes · 4 straight flutes
Chamfer	Form C, 2 – 3 threads
Chip	Short and broken: stays in the flutes or comes out as powder
Thread depth	Up to 2.5 × d
Rake angle	3 – 5°
Tool material	HSS-E; solid carbide on request for high-volume production
Coating	TiCN (first choice) · alternatively nitrided, TiN
Tolerance	6H (6HX on request); 6G and 7G for threads to be galvanised or painted
Design	Reinforced shank from M2 to M10 (DIN 371), reduced shank from M12 (DIN 376); from M3 to M10 also with reduced shank for deep holes
Cutting direction	Right-hand; left-hand on request

Workpiece materials

Group	Cast irons and short-chipping materialsISO KISO N
Strength	up to 300 HB
Examples	grey cast iron EN-GJL (GG20 – GG30), ductile cast iron EN-GJS (GGG40 – GGG60), malleable cast iron; also die-cast aluminium with Si over 10 % and short-chipping brass

Sizes – ISO metric thread

Thread	Pitch P	Tap drill Ø	L overall	l thread	Ø d2 shank	Square a
M2	0,4	1,6	45	8	2,8	2,1
M2,5	0,45	2,05	50	9	2,8	2,1
M3	0,5	2,5	56	11	3,5	2,7
M3,5	0,6	2,9	56	12	4	3
M4	0,7	3,3	63	13	4,5	3,4
M5	0,8	4,2	70	16	6	4,9
M6	1	5	80	19	6	4,9
M8	1,25	6,8	90	22	8	6,2
M10	1,5	8,5	100	24	10	8
M12	1,75	10,2	110	28	9	7
M14	2	12	110	30	11	9
M16	2	14	110	32	12	9
M18	2,5	15,5	125	34	14	11
M20	2,5	17,5	140	34	16	12
M22	2,5	19,5	140	34	18	14,5
M24	3	21	160	38	18	14,5
M27	3	24	160	38	20	16
M30	3,5	26,5	180	45	22	18
M33	3,5	29,5	180	50	25	20
M36	4	32	200	56	28	22

Dimensions in mm. M39 to M100 and fine, pipe and inch threads on request. The tap drill Ø is the one recommended for tolerance 6H.

Coatings for cast irons

Coating	When to choose it
TiCN – titanium carbonitride ★	Harder and more abrasion-resistant than TiN: quenched and tempered steels, cast irons and series production.
Nitriding	Treatment that hardens the tool surface: cast irons and abrasive short-chipping materials.
TiN – titanium nitride	The universal coating: less friction and less sticking, longer life on structural steels and common materials.

★ INNOT first choice for this material. Every tap can be supplied with any coating in the range: specify it in your request.

Starting data

Printable cutting data tableAll the data on this page in an INNOT PDF to keep in the shop.Download PDF

Cutting speed Vc	8 – 20 m/min (lower value for uncoated substrate or machines with a compensating chuck)
Feed	Equal to the thread pitch: synchronised tapping or chuck with axial compensation
Lubrication	Emulsion; grey cast iron also dry with extraction

Thread	Spindle speed (n)
M6	420 – 1.060
M10	250 – 640
M16	160 – 400
M24	110 – 270

Guide values to be adapted to machine, clamping and lubrication. n = Vc × 1000 / (π × d).

Tips for use

Straight flutes retain the broken chips: in deep blind holes blow out or clean the hole between parts.
Grey cast iron also dry with dust extraction; on ductile iron use emulsion.
Also suitable for die-cast aluminium with silicon over 10 % and for short-chipping brass.
Check the tap drill: in cast iron a hole that is too small tears the thread flanks.
Chamfer the hole entry at 90°: clean start and no burr on the first thread.

Selection guide

Material

Through holes

Blind holes

Structural and annealed steelsup to 800 N/mm²

Spiral pointTiN 35° helixTiN

Quenched and tempered and alloy steels800 – 1400 N/mm²

Spiral pointTiCN 40° helixTiCN

Stainless steels450 – 1000 N/mm²

Spiral pointsteam oxide 35° – 40° helixsteam oxide

Cast irons and short chipsup to 300 HB

Straight flutesTiCN

Aluminium and light alloysSi up to 10 %

Spiral pointbright 45° helixbright

↻

Chiplesssteels, stainless steels, aluminium

Forming tapTiN · steam oxide · CrN

Fine, pipe, inch and left-hand threads: special and custom threads.

Need a different tap?

Thread, tolerance, length, substrate and coating: tell us the material, hole type and depth and we will propose the right tap with a quote within 30 minutes.

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